El Ters, Mireille

Background. Recent studies identified underlying genetic causes in a proportion of patients with various forms of kidney disease. In particular, genetic testing reclassified some focal segmental glomerulosclerosis (FSGS) cases into collagen type 4 (COL4)-related nephropathy. This knowledge has major implications for counseling prospective transplant recipients about recurrence risk and screening biologically related donors. We describe our experience incorporating genetic testing in our kidney transplant multidisciplinary practice. Methods. Patients’ DNA was analyzed using whole exome sequencing for a comprehensive kidney gene panel encompassing 344 genes associated with kidney diseases and candidate genes highly expressed in the kidney. Results were correlated with phenotype by a multidisciplinary committee of nephrologists, renal pathologists, geneticists, and genetic counselors. Between October 2018 and July 2020, 30 recipient and 5 donor candidates completed testing. Results. Among recipient candidates, 24 (80%) carried the diagnosis of FSGS, 2 (6.7%) tubulointerstitial nephritis, and 1 (3.3%) nephrolithiasis, and 3 (10%) had an unknown cause of kidney disease. The yield for pathogenic/likely pathogenic variants was 43.3%, with majority being COL4 variants (53.8%). Among those with FSGS diagnosis, the yield was 10 of 24 (41.6%), with 29% reclassified into a COL4-related nephropathy. Family history of kidney disease was the only clinical characteristic difference between recipients with positive and negative results (76.9 versus 29.4%; P = 0.025). One of 5 donors tested positive for a pathogenic/likely pathogenic variant and was excluded from donation. Conclusions. We conclude that thoughtful use of genetic testing can be valuable for kidney donor selection and transplant recipient management.

Background. Improving both patient and graft survival after kidney transplantation are major unmet needs. The goal of this study was to assess risk factors for specific causes of graft loss to determine to what extent patients who develop either death with a functioning graft (DWFG) or graft failure (GF) have similar baseline risk factors for graft loss. Methods. We retrospectively studied all solitary renal transplants performed between January 1, 2006, and December 31, 2018, at 3 centers and determined the specific causes of DWFG and GF. We examined outcomes in different subgroups using competing risk estimates and cause-specific Cox models. Results. Of the 5752 kidney transplants, graft loss occurred in 21.6% (1244) patients, including 12.0% (691) DWFG and 9.6% (553) GF. DWFG was most commonly due to malignancy (20.0%), infection (19.7%), cardiac disease (12.6%) with risk factors of older age and pretransplant dialysis, and diabetes as the cause of renal failure. For GF, alloimmunity (38.7%), glomerular diseases (18.6%), and tubular injury (13.9%) were the major causes. Competing risk incidence models identified diabetes and older recipients with higher rates of both DWFG and nonalloimmune GF. Conclusions. These data suggest that at baseline, 2 distinct populations can be identified who are at high risk for renal allograft loss: a younger, nondiabetic patient group who develops GF due to alloimmunity and an older, more commonly diabetic population who develops DWFG and GF due to a mixture of causes—many nonalloimmune. Individualized management is needed to improve long-term renal allograft survival in the latter group.

Significance Statement Treatment of proliferative GN with monoclonal Ig deposition (PGNMID), in which direct deposition of the monoclonal proteins damages the kidney, is not established. Daratumumab, a monoclonal anti-CD38 antibody, has shown effectiveness as multiple myeloma therapy. In an open-label, phase 2 study, the authors evaluated safety and efficacy of a 6-month course of intravenous daratumumab in 11 patients with PGNMID and one with C3 glomerulopathy with monoclonal gammopathy. Five episodes of serious adverse events (two of which were infection related) occurred. All ten patients with PGNMID who received at least one daratumumab dose experienced a significant reduction in proteinuria at 6 months, which was sustained in seven patients by 12 months. Overall, in this pilot study, daratumumab’s acceptable toxicity profile and significant improvement in proteinuria, while stabilizing kidney function, suggest further investigation is warranted. Background Treatment of proliferative GN with monoclonal Ig deposits (PGNMID) is not established. A monoclonal anti-CD38 antibody (daratumumab) is effective in treating multiple myeloma. Abnormal plasma cell clones may play a role in the pathogenesis of PGNMID. Methods We evaluated daratumumab’s safety and efficacy in an open-label, phase 2 trial in 11 adults with PGNMID and one with C3 glomerulopathy (C3G) with monoclonal gammopathy. Patients had an eGFR >20 ml/min per 1.73 m 2 and proteinuria >1 g/d. They received daratumumab intravenously (16 mg/kg) once weekly for 8 weeks, and then every other week for eight additional doses. Primary outcome was safety, defined as major infections, grade 3 or 4 anemia, leukopenia, or thrombocytopenia. Secondary outcomes were rate of complete remission (proteinuria <500 mg/d with <15% decline in baseline eGFR) or partial remission (>50% reduction in 24-hour proteinuria with <30% decline in eGFR) and proteinuria at 6 and 12 months. Results One patient with C3G had GN unrelated to the monoclonal gammopathy, and one with PGNMID did not complete the first infusion. Five serious adverse events occurred. During the 12 months of the trial, six of the ten patients with PGNMID who received at least one dose of daratumumab had a partial response, and four had a complete response (an overall response rate of 100%). Three patients experienced relapse, two of whom re-entered partial remission after resuming daratumumab therapy. Proteinuria declined significantly, from a median of 4346 mg/d to 1264 mg/d by 12 months. Conclusions Daratumumab demonstrated an acceptable safety profile and resulted in significant improvement in proteinuria while stabilizing kidney function in patients with PGNMID, suggesting the drug merits further investigation. Clinical Trial registry name and registration number: Daratumumab in Treatment of PGNMID and C3 GN, NCT03095118

Background. Experience with sequential hematopoietic stem cell transplant (HSCT) and kidney transplant (KT) is limited. Methods. We conducted a retrospective observational study of adult patients who underwent both HSCT and KT at our center, with a median follow-up of 11 y. Results. In our 54 patients cohort (94% autologous HSCT), 36 (67%) patients received HSCT first followed by KT, while 18 (33%) received KT before HSCT. In both groups, AL amyloidosis represented 50% of hematologic diagnosis. Only 4 patients expired due to hematologic disease relapse (2 patients in each group) and only 3 allografts were lost due to hematologic disease recurrence (HSCT first n = 1 and KT first n = 2). Overall 1, 5, and 10 y death-censored graft survival rates were 94%, 94%, and 94%, respectively, for the HSCT first group and 89%, 89%, and 75%, respectively, for the KT first group. Overall 1, 5, and 10 y patients survival rates were 100%, 97% and 90%, respectively, for the HSCT first group and 100%, 76%, and 63%, respectively, for the KT first group. Conclusions. Our study supports safety of sequential KT and HSCT, with improved overall patient survival compared to recipients of HSCT remaining on dialysis and good long-term kidney allograft outcome.

Background. Graft survival after kidney transplant (KTX) is often estimated by the Kaplan-Meier (KM) method censoring for competing endpoints, primarily death. This method overestimates the incidence of graft loss. Methods. In 3157 adult KTX recipients followed for a mean of 79.2 months, we compared kidney and patient survival probabilities by KM versus competing risk analysis (CRA). These methods are extended to comparing different regression methods. Results. Compared with CRA, the probabilities of death and graft loss (censored for the other outcome) were substantially higher by KM. These differences increased with increasing follow-up time. Importantly, differences in graft losses were magnified in subgroups with greater probabilities of death. Among recipients with diabetes, the probabilities of graft loss at 20 years were 57% by KM and 32% by CRA, while for non-diabetes mellitus corresponding values were 44% and 35%. Similar results are noted when comparing older versus younger recipients. Finally, we find that the Fine-Gray method assumptions are violated when using age and gender as covariates and that the alternative method of Aalen-Johansen may be more appropriate. Conclusions. CRA provides more accurate estimates of long-term graft survival and death, particularly in subgroups of recipients with higher rates of the competing event. Overestimation of risk by KM leads to both quantitative and qualitative misinterpretations of long-term KTX outcomes. When using regression analyses, care should be taken to check assumptions to guide the choice of appropriate method.

Background. Proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) is a distinct form of glomerulonephritis that often recurs after kidney transplantation causing severe graft injury and often failure. Methods. We describe post transplant outcomes and response to therapy in 20 recipients with PGNMID. Evidence of PGNMID recurrence or lack thereof was determined by protocol and clinical biopsies. Results. Histologic recurrence (deposition of monoclonal immunoglobulin) occurred in 18 of 20 recipients (90%), a median of 7 (1 to 65) months post transplant. At diagnosis, recurrence was generally associated with mild or no clinical manifestations and often with mild glomerular morphologic changes by light microcopy. Four of the 18 patients with recurrence did not progress and were not treated. Another 4 patients with recurrences were treated with cyclophosphamide with or without plasmapheresis, and 2 of these grafts were lost from glomerulonephritis. Nine patients with recurrences were treated with anti-CD20 antibodies (rituximab) alone, resulting in improvements in estimated glomerular filtration rate (31.5 ± 16 versus 38.8 ± 13.3 mL/min/1.73 m 2 , P = 0.011) and proteinuria (1280 [117 to 3752] versus 168 [83 to 1613] mg/24 h, P = 0.012) although complete clinical remission was rare. One graft in this later group was lost from recurrence 141 months post transplant. Posttreatment biopsies demonstrated stable or improved glomerular histology in most cases. However, PGNMID did not resolve in any case. Four patients received rituximab 4 months pretransplant to prevent recurrence. However, 3 had mild recurrences. Conclusions. Rituximab treatment of early PGNMID recurrence is effective, resulting in reasonable, long-term graft survival. Whether pretransplant rituximab modifies the course of recurrence requires additional studies.